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Xu C.-Y.,Capitol University | Xu C.-Y.,Beijing Institute of Heart Lung and Blood Vessel Diseases | Liu X.-J.,Capitol University | Liu X.-J.,Beijing Institute of Heart Lung and Blood Vessel Diseases | And 7 more authors.
Chinese Journal of Biomedical Engineering | Year: 2014

Sheep models are often used to verify the blood compatibility, biological safety and reliability of VADs as well as the impact on physiological conditions of animals. Effective and safe anticoagulation regimens are strongly needed to reduce risks of thrombosis and bleeding. This study is to evaluate the effect of anticoagulation for animals after implantation of CH-VAD with heparin and warfarin, aiming to offer anticoagulation data for long-term survival experiments and clinical applications. CH-VAD models were established in six healthy sheep by constructing blood bypass of left ventricular →VAD → descending aorta. Heparin of 250 U/kg was injected through jugular vein during operation. Continuous heparin infusion was used in the prior four days after implantation to keep ACT and aPTT values as 1.5 to 2. 0 times as the baseline. From the third day, proper dosage of warfarin was used orally to make INR in the target range of 1. 2 ∼ 2. 0. Bleeding complications were closely monitored through the experiment. At the termination point, we examined whether there was thrombosis in the blood pump, grafts and anastomotic stoma. Macroscopical examinations were performed in major organs to check congestion and infarction. Tissues of the organs were collected to make HE staining to evaluate histopathological changes. Bleeding complications were not found in all animals throughout the experiments. Intraoperative ACT values were (326 ± 33) s. ACT values were(157 ±28)s in the prior four days, reaching the target range. The aPTT increased slowly and reached the lower limit of the target range at the fourth day. No thrombosis and fibrosis tissue were found in blood flow channel except for Sheep4. Pathological images showed no thrombosis, necrosis and microembolus in end-stage organs under the anticoagulation regimen. Under the anticoagulation regimen of continuous intravenous heparin maintaining ACT 1.5 ∼2.0 times the baseline and later oral warfarin maintaining INR values within the range of 1.2 ∼ 2. 0, thrombosis and bleeding complications could be well controlled in sheep models for CH-VAD, providing reference for later animal experiments.

Liu X.-J.,Capital Medical University | Liu X.-J.,Beijing Institute of Heart Lung and Blood Vessel Diseases | Wu G.-H.,Capital Medical University | Wu G.-H.,Beijing Institute of Heart Lung and Blood Vessel Diseases | And 10 more authors.
Chinese Journal of Biomedical Engineering | Year: 2012

An in vivo experimental investigation was performed in ovine model to evaluate hemocompatibility, reliability and end-organ effects of the ChinaHeart VAD, a magnetic left ventricular assist device. The device was implanted in 6 healthy male sheep. Under anesthesia, via left lateral thoracotomy, the inflow cannula was inserted into the left ventricular apex on beating hearts, and the outflow graft was anastomosed to the descending aorta. Routine hematologic and biochemical tests were performed preoperatively and postoperatively to evaluate peripheral organ functions. Pump operating parameters were recorded continuously until termination of the experiment. At the end of the experimental period the sheep was humanely killed, and the end-organs were examined macroscopically and histopathologically. Two of the 6 animals survived for 20 and 38 days, the other four died of anesthesia or blood leakage at the inflow cannula or outflow graft within the first 3 to 28 hours. For the two survival animals, hematological and biochemical data showed no evidence of organ dysfunction during the experimental period. At autopsy, one small thrombosis formatted at the bottom housing in one pump (20-day survival sheep), but no other thrombosis was found in the ventricular cavity of both two sheep. In addition, except lobular pneumonia was observed the left lung lobe adjacent to the pump, there were no histological changes in the other major end-organs. The ChinaHeart VAD system demonstrated excellent hemocompatibility and reliability for more than 20 days, and had no significant side effect on the major end-organs. In addition, aneshesia management and surgical procedures are crucial in animal survived experiment.

Yin C.,Soochow University of China | Yin C.,China Heart Biomedical Inc | Tan X.,China Heart Biomedical Inc | Qu W.,China Heart Biomedical Inc | And 3 more authors.
Chinese Journal of Sensors and Actuators | Year: 2012

Noncontact eddy current displacement sensor was designed for the Maglev system of the ventricle assist device ( VAD ). With regard to the special structure in which there was a titanium alloy frame between the displacement sensor and VAD's rotor,this paper analyzed the sensor magnetic field by using finite element method to obtain structural parameters of sensor, built a device to monitor coil winding for improving the impedance consistency. Performance test of sensor coils shows that the standard deviation of sensor coils is 3. 8% , the sensitivity is higher than 10% ,and the good properties are feasible for the Maglev system of VAD.

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